The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Fluid filled vibration damping devices are utilized for automotive engine mounts, subframe mounts and body mounts. These vibration damping devices couple two components together while damping the vibrations between the components. Typically there is an upper portion and a lower portion precompressed against each other prior to the working load being applied to the mounting system.
Current fluid filled elastomeric damping devices such as suspension bushings, body mounts, engine mounts and sub-frame mounts typically use glycol or glycol water solutions as the fluid of choice. Common fluids used in this category of vibration damping devices are 50% ethylene glycol/50% water or 50% propylene glycol/50% water mixtures.
Current industry trends are to use propylene glycol mixtures due to the lower toxicity concerns with propylene glycol over ethylene glycol. Any of the simple diols that are fully soluble with water are appropriate fluids to choose from. These include ethylene glycol, propylene glycol, di-proylene glycol and tri-propylene glycol. Other more complicated chemical structure glycols could be used in their pure forms or at mixture ratios that support full solubility with water over a temperature range of −40° C. to 105° C.
The main disadvantage of these solutions are their densities being in the range of 1.0 g/cm3 to 1.1 g/cm3 and their viscosity profile over the temperature range indicated above.
Fluid filled vibration damping elastomeric devices of the type listed above work on the principle of resonant masses. These devices have internal geometric fluid flow pathways that allow a mass of fluid to go into a natural resonance based on the geometric shape of the fluid pathway, the fluid density, the fluid viscosity and the fluid surface tension. The fluids used also have to have a freezing point below −40° C. and a boiling point above 105° C. to meet the targeted end use applications encountered in the transportation vehicle industry.
Improved fluid filled vibration damping devices could be built if alternative fluid having improved properties when compared with the current state of art fluids were used.